1. Field of the Invention:
The present invention is directed to the bobbin assembly for a soldering/desoldering device. More particularly, the present invention relates to an improved heater assembly and method of assembling the same.
2. Description of the Prior Art:
It is known in the art to utilize metal deposited foil heaters, which are axially disposed with respect to the soldering/desoldering device. In particular, such heaters are prepared by depositing (e.g., vapor depositing or sputtering) a metal heater element (by use of an appropriate mask) on a flexible ceramic (an unfired ceramic). This flexible ceramic is then wrapped about a ceramic bobbin so that the deposited metal foil heater is sandwiched between the ceramic bobbin and the flexible ceramic. This composite structure is then fired to cure the flexible ceramic. As will be appreciated, the heater cannot be separately tested when manufactured in this manner, since the "green" (unfired) ceramic upon which it is deposited is itself electrically conductive. Thus, the heater may only be tested after firing of the "green" ceramic, however, after firing, it is too late to take any corrective action and any faulty heater circuits must be discarded. Additionally, the ceramic bobbin has a thickness of about 0.125 inch, while the flexible ceramic, upon which the heater element is deposited and which is wrapped around the ceramic bobbin, has a thickness of 0.005-0.010 inch. Thus, the tendency in this type of heater construction is for excessive amounts of radiative heat dissipation since there is less resistance to the outward flow of heat from the assembled unit.
It is further known in the art to utilize a resistance wire wrapped around a bobbin as the heater element of a bobbin assembly for a soldering/desoldering device.
It is also known in the art to place a thermocouple in close proximity to the tip of a soldering/desoldering device so as to measure the temperature thereof (or an approximation of the tip temperature). This measured temperature is then used to control the electric power supply to the heater assembly to maintain a desired temperature of the tip. However, such indirect measurement of the tip temperature is hindered by the buildup of corrosion layers between the tip and the thermocouple, there corrosion layers retard heat transfer and thus produce inaccurate temperature readings.